Azurophil Granule Proteins Constitute the Major Mycobactericidal Proteins in Human Neutrophils and Enhance the Killing of Mycobacteria in Macrophages
Open Access
- 14 December 2012
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLOS ONE
- Vol. 7 (12), e50345
- https://doi.org/10.1371/journal.pone.0050345
Abstract
Pathogenic mycobacteria reside in, and are in turn controlled by, macrophages. However, emerging data suggest that neutrophils also play a critical role in innate immunity to tuberculosis, presumably by their different antibacterial granule proteins. In this study, we purified neutrophil azurophil and specific granules and systematically analyzed the antimycobacterial activity of some purified azurophil and specific granule proteins against M. smegmatis, M. bovis-BCG and M. tuberculosis H37Rv. Using gel overlay and colony forming unit assays we showed that the defensin-depleted azurophil granule proteins (AZP) were more active against mycobacteria compared to other granule proteins and cytosolic proteins. The proteins showing antimycobacterial activity were identified by MALDI-TOF mass spectrometry. Electron microscopic studies demonstrate that the AZP disintegrate bacterial cell membrane resulting in killing of mycobacteria. Exogenous addition of AZP to murine macrophage RAW 264.7, THP-1 and peripheral blood monocyte-derived macrophages significantly reduced the intracellular survival of mycobacteria without exhibiting cytotoxic activity on macrophages. Immunofluorescence studies showed that macrophages actively endocytose neutrophil granular proteins. Treatment with AZP resulted in increase in co-localization of BCG containing phagosomes with lysosomes but not in increase of autophagy. These data demonstrate that neutrophil azurophil proteins may play an important role in controlling intracellular survival of mycobacteria in macrophages.This publication has 53 references indexed in Scilit:
- An interferon-inducible neutrophil-driven blood transcriptional signature in human tuberculosisNature, 2010
- Vitamin D3 Induces Autophagy in Human Monocytes/Macrophages via CathelicidinCell Host & Microbe, 2009
- Neutrophil primary granule proteins HBP and HNP1–3 boost bacterial phagocytosis by human and murine macrophagesJCI Insight, 2008
- Neutrophil-mediated innate immune resistance to mycobacteriaJCI Insight, 2007
- Role of Human Neutrophil Peptide–1 as a Possible Adjunct to Antituberculosis ChemotherapyThe Journal of Infectious Diseases, 2004
- Neutrophil Extracellular Traps Kill BacteriaScience, 2004
- Therapeutic Potential of Human Neutrophil Peptide 1 against Experimental TuberculosisAntimicrobial Agents and Chemotherapy, 2001
- Enhanced interleukin-8 release and gene expression in macrophages after exposure to Mycobacterium tuberculosis and its components.JCI Insight, 1995
- Ultrasensitive assays for endogenous antimicrobial polypeptidesJournal of Immunological Methods, 1991
- Host and bacterial factors control theMycobacterium avium-induced chronic peritoneal granulocytosis in miceClinical and Experimental Immunology, 1991